Oregon off-grid system - Is this looking good?

[PNW_Solar_Guy]

Hi All,

I've been reading through a number of threads on the forum, it's great to see so much support on here.

I essentially have no experience with solar but I would love to learn from some of you much more experienced folk out there on the system we are working on so far.

We have 65 acres in Oregon and were told by the electric company that it would cost $25k to tie us in to the grid. We were already thinking solar down the line, but that grid tie in price tag pushed us over the edge.

We plan to build a farm garage/outbuilding on that corner of the property (where there is no power), and then in a few years build a home next to it. We want this system to be expandable so we have plenty of power for both buildings by that point. But we're starting with just enough power for the garage/outbuilding for now.

I've attached our electrical design file to this thread, as well as a list (below) of the main details. If I'm omitting something please do reply and ask for it. I'm prepared to receive constructive criticism on this, as it's our first go at putting together plans for an off-grid solar system.

System details
Solar Array
Mount type: ground mount (adjustable between 18-65 degrees for our region)
Total panels / arrays (current): 70 / 5
Total kW (current): 32.2kW
Total panels / arrays (eventual): 120 / 9
Total kW (eventual): 55.2kW
Panel info: BlueSun 460w bifacial (model BSM460M-72HBD)
Panel configuration: 7S2P
Notes: Arrays are located exactly 300ft from the solar shed, where the inverters and batteries will be stored

Inverters
Desired AC output: 120/240v split phase power
Inverter model: MPP Solar LVX6048
Total inverters (current): 5 (in parallel)
Total inverters (eventual): 9 (in parallel)
**(Is this overkill? Should I just purchase cheaper charge controllers, and then one or two split phase inverters for the 120/240v service I need, instead of 5-9 LVX6048's?

Batteries
Battery model: Pytes LiFePO4 48V 5.1kWh battery
Total batteries (current): 5 (in parallel)
Total batteries (eventual): 20 (in parallel)

Loads
The buried line from the load panels in the solar shed to the garage (and eventually the house too) is exactly 170ft.
For our garage/outbuilding, we expect the loads to be minimal, between 10-20kw/day depending on the work that is being done there. In a few years when the house is built next to it, we expect the daily load to be between 60-80kw/day. We will have our main load suckers (heater, range/oven, hot water heater, dryer) all running off of our LP tank buried outside

I hope this is enough information to paint the broad strokes. I'm hoping to borrow some of your wisdom on this one as I am certain there are element's that I'm overlooking and that I need to dive more deeply into.

Cheers!

 

[JonnyWatt]

Love your vision. I'm looking to similar design with LV6548's in parallel, Blue Sun bifacial 460W panels, and 5.1KW Pytes or SOK bank. Why did you choose Pytes?

 

[OffGridInTheCity]

Batteries
Battery model: Pytes LiFePO4 48V 5.1kWh battery
Total batteries (current): 5 (in parallel)

5 x 5.1kwh = 25.5kwh. I think you'll find a 25kwh battery bank too small to be able to have an even load all 24hrs of a day on a 33kw PV array.

I run a 13kw PV array in Southern Oregon (Medford) with an 81kwh battery bank and need a 40% DOD to be able to use all the power produced. My average consumption is 2,679kw/hour x 24hrs a day = 64.3kwh/day average. If I had a 41kwh battery bank I'd need an 80% DOD.

Total batteries (eventual): 20 (in parallel)

My ratio suggests 40kwh battery bank per 13kw PV array at 80% DOD. A 55kw PV array needs something on the order of 200kwh battery bank at 80% DOD.

*I agree that consumption and consumption patters affect this greatly - and I always recommend starting smaller and learning! and then expand as needed. I would leave room in your planning or a larger battery than you're currently thinking.

A KEY issue is winter. In summer, my 13kw PV array produces 70kwh/day but in winter it runs 20% of summer. By extrapolation, a 55kw PV array would produce 300kwh/day in summer and 60kwh/day in winter. This last December (Dec 2021) was extra harsh and I only got 10% of summer. For me it was 7kwh/day and for your 55kw PV array it would be on the order of 30kwh/day.

13kw PV - kwhs by month


I have 'some' propane generator backup (60days) but also 42 panels (12kw) under the house for winter / emergency deployment to the back yard IF there were to be a Puerto Rico type event and grid was down for months.

Loads
The buried line from the load panels in the solar shed to the garage (and eventually the house too) is exactly 170ft.

170ft isn't that far. Proper wire size and voltage will easily mitigate losses.

For our garage/outbuilding, we expect the loads to be minimal, between 10-20kw/day depending on the work that is being done there. In a few years when the house is built next to it, we expect the daily load to be between 60-80kw/day. We will have our main load suckers (heater, range/oven, hot water heater, dryer) all running off of our LP tank buried outside

Except for the battery sizing, I think you're on a good track. Its the kind of system I would think about if I had a large property!!

FYI - I've found PVWatts a good tool to estimate PV generation for specific locations - https://pvwatts.nrel.gov/pvwatts.php. It's been within 20% of reality for me.

 

[PNW_Solar_Guy]

Love your vision. I'm looking to similar design with LV6548's in parallel, Blue Sun bifacial 460W panels, and 5.1KW Pytes or SOK bank. Why did you choose Pytes?

Thanks, @JonnyWatt! It's been a steep learning curve as I'm not well-versed in electric in any way. I'm a sponge though when I get onto something that interests me and in this case it's not only interesting but it will also (eventually) save us $, so now I am even more eager to nail down the best system for our needs.

As for the Pytes selection, we really liked what Ian at Watts247 had to say about them in his videos as well as directly over the phone. The manufacturer also appears to have a long track record of quality battery production (albeit under a different name previously), so from a build and cell quality standpoint, they seem to check out. I looked into EG4's offerings as well as a few others but I kept coming back to Pytes. Oh I also liked their cable linking style as it seems to make for easy and safe paralleling of units.

 

[JonnyWatt]

I too was leaning toward Pytes. I spent yesterday reviewing Ian's site videos and his Silicate batteries caught my attention (see link below). In one of his videos, he said his Silicaate batteries likely the only batteries that will remain working after an EMP event - along with lead acid batteries. I was looking for 20KW Pytes but can get Silica 24KW for $1000 less. The con is they weigh about 170lbs each for 12V 250A Silicate, but once you have then in place, should no longer be an issue. The pros are 1) less expensive, 2) more robust as can charge and function in below zero weather, and 3) no BMS to fail from surge. If I don't get Silicates, I plan to get Pytes though.

Special!12kWH Silicate Battery 12/24/48V Best Price per kWh -15 yrs -6000 Cycles at 30% 8yr3000cl at 60% – Temp -40F to 150F -NO BMS or Thermal Protection required, Non Corrosive explosive, A Count of 4 x 12v 250AH – Watts247 Wholesale

watts247.com

 

[PNW_Solar_Guy]

5 x 5.1kwh = 25.5kwh. I think you'll find a 25kwh battery bank too small to be able to have an even load all 24hrs of a day on a 33kw PV array.

I run a 13kw PV array in Southern Oregon (Medford) with an 81kwh battery bank and need a 40% DOD to be able to use all the power produced. My average consumption is 2,679kw/hour x 24hrs a day = 64.3kwh/day average. If I had a 41kwh battery bank I'd need an 80% DOD.


My ratio suggests 40kwh battery bank per 13kw PV array at 80% DOD. A 55kw PV array needs something on the order of 200kwh battery bank at 80% DOD.

*I agree that consumption and consumption patters affect this greatly - and I always recommend starting smaller and learning! and then expand as needed. I would leave room in your planning or a larger battery than you're currently thinking.

A KEY issue is winter. In summer, my 13kw PV array produces 70kwh/day but in winter it runs 20% of summer. By extrapolation, a 55kw PV array would produce 300kwh/day in summer and 60kwh/day in winter. This last December (Dec 2021) was extra harsh and I only got 10% of summer. For me it was 7kwh/day and for your 55kw PV array it would be on the order of 30kwh/day.

13kw PV - kwhs by month
View attachment 93335

I have 'some' propane generator backup (60days) but also 42 panels (12kw) under the house for winter / emergency deployment to the back yard IF there were to be a Puerto Rico type event and grid was down for months.


170ft isn't that far. Proper wire size and voltage will easily mitigate losses.


Except for the battery sizing, I think you're on a good track. Its the kind of system I would think about if I had a large property!!

FYI - I've found PVWatts a good tool to estimate PV generation for specific locations - https://pvwatts.nrel.gov/pvwatts.php. It's been within 20% of reality for me.

Hi OffGridInTheCity, wow this is exactly what I was hoping to hear from someone on this forum, thank you! I had the same thought regarding the total battery capacity. It's good to know that you also live in Oregon, so we have similar solar situations. I was also leaning toward beefing up on my batteries--the more deeply I got into the planning on this project, the more I began to realize that I could negatively impact the health of the batteries by overloading them and drawing them below the recommended DOD. My initial loads will be light, as it will just be the occasional power tool or set of tools, to use as we build out there. But invariably we'll end up using more than anticipated (heaters, etc) and I'm sure it won't be long before I'll need to stack another server rack in place to increase our total capacity.

It also sounds like you're relying solely on your PV for house power, is that right? That's admirable and what I eventually aim to do too. To start, we will be installing a 1,000 gal LP tank to take the brunt of the heavy lifting items off the solar system's plate, such as the house heat, hot water heater, dryer and oven/range. My hope is that having those heavy hitters drawing from the LP tank, it'll buy us time to build out the solar system (battery storage as well as more panels as needed), until we are able to start pulling some of those heavy hitters off of the LP (eventually all, would be great).

Also that's excellent to know that the 170' AC run won't be too much. Hadn't done the math on that yet, so was relying on crossed fingers until just now.

Yes, I did try out the PVWatts.com calculator and used it to get some of our initial calculations. Excellent source of info.

Again much appreciated, OffGridInTheCity. I will likely update this thread as I begin my build, I am 100% certain I'll have loads more questions when the rubber starts to meet the road!

 

[PNW_Solar_Guy]

I too was leaning toward Pytes. I spent yesterday reviewing Ian's site videos and his Silicate batteries caught my attention (see link below). In one of his videos, he said his Silicaate batteries likely the only batteries that will remain working after an EMP event - along with lead acid batteries. I was looking for 20KW Pytes but can get Silica 24KW for $1000 less. The con is they weigh about 170lbs each for 12V 250A Silicate, but once you have then in place, should no longer be an issue. The pros are 1) less expensive, 2) more robust as can charge and function in below zero weather, and 3) no BMS to fail from surge. If I don't get Silicates, I plan to get Pytes though.

Special!12kWH Silicate Battery 12/24/48V Best Price per kWh -15 yrs -6000 Cycles at 30% 8yr3000cl at 60% – Temp -40F to 150F -NO BMS or Thermal Protection required, Non Corrosive explosive, A Count of 4 x 12v 250AH – Watts247 Wholesale

watts247.com

Ah that's good to know! Ian told me the same thing. I hadn't thought about the EMP end of this. I know the Pytes has military spec BMS modules but I didn't think to check whether that somehow covers EMP. Am going to look into that further before I officially lock in with Pytes. Keep me posted on what you decide to go with too, it sounds like we have pretty similar system's in mind.

 

[JonnyWatt]

Ah that's good to know! Ian told me the same thing. I hadn't thought about the EMP end of this. I know the Pytes has military spec BMS modules but I didn't think to check whether that somehow covers EMP. Am going to look into that further before I officially lock in with Pytes. Keep me posted on what you decide to go with too, it sounds like we have pretty similar system's in mind.

Thanks PNW. I know its impossible to fully plan for EMP event, but batteries are an easy solution towards that goal. I have a message queued up for Ian to ask a few more EMP related questions. One is: does he sell spare boards for LV6548 and combiners that I can put in Faraday bag for backup for such an event. I also was thinking of buying the new EG4 3kW Off-Grid Inverter (Signature Solar) as emergency backup that can put in Faraday bag as tiny. Will Prowse just reviewed it and sounds pretty nice for "some" power if lose LV6548s, but would take 4 EGR 3KW to replace 2 LV6548s. I've read that the diodes on solar panels would fry; I have no idea how difficult it would be to replace these. I have already purchased my Blue Sun bifacials (same as yours) so we do seem to be heading in the same direction, but your system is far bigger!

 

[PNW_Solar_Guy]

Thanks PNW. I know its impossible to fully plan for EMP event, but batteries are an easy solution towards that goal. I have a message queued up for Ian to ask a few more EMP related questions. One is: does he sell spare boards for LV6548 and combiners that I can put in Faraday bag for backup for such an event. I also was thinking of buying the new EG4 3kW Off-Grid Inverter (Signature Solar) as emergency backup that can put in Faraday bag as tiny. Will Prowse just reviewed it and sounds pretty nice for "some" power if lose LV6548s, but would take 4 EGR 3KW to replace 2 LV6548s. I've read that the diodes on solar panels would fry; I have no idea how difficult it would be to replace these. I have already purchased my Blue Sun bifacials (same as yours) so we do seem to be heading in the same direction, but your system is far bigger!

I saw those new EG4 inverters as well, they seem decent actually, though you're exactly right about not providing much power. It would be great if we could coat the interior of our solar shed with a material that would protect all of the components inside (battery BMS, inverter electronics, etc). I might have to look into that. Like a whole-shed faraday cage. Worth looking into, it can get expensive buying duplicates of everything, let alone just the original units!

 

[JonnyWatt]

Totally agree PNW. My understanding to EMP a room is tens of thousands of dollars. Doorways, windows, and even pipes in/out of room must be hardened at ridiculous prices. Here is an example of an EMP portable room 4ft x 4ft x 6ft tall to illustrate how expensive this technology is, and it will not accommodate wires coming in/out of room for $25K:

Hardwall Modular Faraday Enclosure – RF/EMI Portable Shielding Room (4′ x 4′ x 6.5′) – FARADAY DEFENSE

shop.faradaydefense.com

The better solution would be a good military spec Faraday Bag to hold some spare inverter boards. Here's a duffle bag from Mission Darkness for $300 that would hold 3 of the EG4 3K units (case and all) and more if just the electronic boards could be purchased. Note: a LV6548 will NOT fit in this bag, but Mission darkness does make a bag that would hold six LV6548s for $1000 (see below).

The smaller bag could also be put in a metal trash can for extra layer of protection. I sent message today to Signature Solar asking if EG4 3KW units guts (boards) would be available to purchase separately.

Small Mission Darkness bag $300 (hold 3-EGR 3KW units)

Mission Darkness™ X2 Faraday Duffel Bag

March 17, 2022: Notice! Due to recent world events this item has been in high demand. Current lead time is 4-6 weeks. Place orders now to hold your items! Keep Large Devices Shielded With the X2 Faraday Duffel Bag...

mosequipment.com

MidSize Mission Darkness bag $580 (hold 2-LV6548)

https://www.amazon.com/Mission-Darkness-Electronics-Military-Grade-Investigators/dp/B076XQDZVG/ref=sr_1_6?crid=36NQIM992ZZW8&keywords=mission+darkness&qid=1651863125&sprefix=mission+darkness+%2Caps%2C101&sr=8-6

Large Mission Darkness bag $1000 (hold 6-LV6548)

https://www.amazon.com/Mission-Darkness-Weatherproof-Signalproof-electromagnetic/dp/B0876FKWDV/ref=sr_1_1_sspa?crid=36NQIM992ZZW8&keywords=mission+darkness&qid=1651862251&sprefix=mission+darkness+%2Caps%2C101&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzTEFQQU0wNjdGMUxUJmVuY3J5cHRlZElkPUEwNTk4ODc0MzMzNlQ4RVQxV0RDUiZlbmNyeXB0ZWRBZElkPUExMDQzNTM2M0NLMTZFVDgyOVNNOCZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[JonnyWatt]

I thought I should ad I have backed away from Silicon Gel batteries. I was drawn to them as protection from EMP event and batteries less costly. The bottom line is Lithium technology is so much cheaper when consider DOD and life cycles. I think I will go with SOK Rack Mount Will Prowse endorses as these batteries can be taken apart and BMS replaced if needed. So, will go with these and buy spare BMS boards to put in Faraday bag. Besides this replaceable BMS feature of the SOKs, I would go with Pytes. Hope your planning is coming along well PNW!

 

[RV10flyer]

Total electric, except Honeywell 10kW Generator- LP and small free standing wood burner for backups.

20.6kW at 45deg, 2 - Sol-Ark12K, 132kWh battery for house. Love it. Off-grid 10 weeks.

Adding: 13.3kW at 45deg, 1 - Sol-Ark12K, 27 kWh battery for shop.

 

[kromc5]

The pdfs were nicely done, you will be very close to my pv capacity. We are all electric and even in winter time even with our current setup is difficult. It's not lack of production but the short days with clouds in the winter. I would go big on the batteries depending your loads if they are similiar or higher to what I posted.